The present invention relates to a cooling structure which ventilates and cools cards consisting of electronic components on circuit boards by using a fan.
Heat generating electronic components such as integrated circuit chips mounted on a printed circuit board of a card which is mounted on a mother board in parallel with other cards are cooled by sending cooling air from a fan disposed above the group of cards and/or a fan disposed under the group of cards. The cards are different from each other in calorific value. As disclosed in Japanese Patent Unexamined Publication No. 153398/83, for example, therefore, means are provided for adjusting a flow rate of air used for cooling cards having low calorific values, in order to control air flow depending upon the calorific values of the cards. Since cards are different from each other in function and hence in component arrangement, however, the cards have different cooling areas. Further, the flow rate adjustment means on a certain card affects the air flow rates directed to all of other cards. Therefore, it is not easy to distribute cooling air at desired ratios among the respective cards.